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RE: x86 Linux stack alignment requirement


> > I see.  Provided a local is passed in a register to a 
> non-vararg function, it is still OK to align the stack.
> 
> Given that we don't support 4 byte aligned stack at all with XMM
> regisrers, I would prefer to increase Linux/x86 stack alignment to
> 16 byte. People can use 4 byte alignment if they want. As for the
> existing 4 byte aligned code, -mstackrealign can be used to support
> them.

It would still be possible for the function to align its stack to 16 bytes, even though it can only assume it to be aligned at 4 bytes upon entry, if it needs it.  Much like -mstackrealign, but paying its cost only in functions that will benefit from it.

-- 
_______________________________________________________
Evandro Menezes               AMD            Austin, TX



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